Abstract
A dilution refrigerator of 80-730μmol/s3He circulation rate has been built and the lowest temperature of 2.85mK is continuously attained. In this refrigerator, the discrete heat exchangers with pressed metal (Cu and Ag) powder are used. These discrete heat exchangers are newly developed based on the analysis of Radebaugh and Siegwarth. The machine is designed for many uses such as a base of nuclear cooling and studies of general solid state physics. The design and construction of the heat exchangers and the mixing chamber are described in part I. And the design and construction of the other parts and the performance of the refrigerator will be described in part II.
